title: Elastic modulus and collagen organization of the rabbit cornea: epithelium to endothelium.
abstract: The rabbit is commonly used to evaluate new corneal prosthetics and study corneal wound healing. Knowledge of the stiffness of the rabbit cornea would better inform the design and fabrication of keratoprosthetics and substrates with relevant mechanical properties for in vitro investigations of corneal cellular behavior. This study determined the elastic modulus of the rabbit corneal epithelium, anterior basement membrane (ABM), anterior and posterior stroma, Descemet's membrane (DM) and endothelium using atomic force microscopy (AFM). In addition, three-dimensional collagen fiber organization of the rabbit cornea was determined using nonlinear optical high-resolution macroscopy. The elastic modulus as determined by AFM for each corneal layer was: epithelium, 0.57 ± 0.29 kPa (mean ± SD); ABM, 4.5 ± 1.2 kPa, anterior stroma, 1.1 ± 0.6 kPa; posterior stroma, 0.38 ± 0.22 kPa; DM, 11.7 ± 7.4 kPa; and endothelium, 4.1 ± 1.7 kPa. The biophysical properties, including the elastic modulus, are unique for each layer of the rabbit cornea and are dramatically softer in comparison to the corresponding regions of the human cornea. Collagen fiber organization is also dramatically different between the two species, with markedly less intertwining observed in the rabbit vs. human cornea. Given that the substratum stiffness considerably alters the corneal cell behavior, keratoprosthetics that incorporate mechanical properties simulating the native human cornea may not elicit optimal cellular performance in rabbit corneas that have dramatically different elastic moduli. These data should allow for the design of substrates that better mimic the biomechanical properties of the corneal cellular environment.
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
authors.forename: Sara M
authors.initials: SM
authors.lastname: Thomasy
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
authors.forename: Vijay Krishna
authors.initials: VK
authors.lastname: Raghunathan
authors.affiliation: Department of Biomedical Engineering, University of California-Irvine, Irvine, CA, USA.
authors.forename: Moritz
authors.initials: M
authors.lastname: Winkler
authors.affiliation: Department of Pathology, Immunology and Microbiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Reilly
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
authors.forename: Adeline R
authors.initials: AR
authors.lastname: Sadeli
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
authors.forename: Paul
authors.initials: P
authors.lastname: Russell
authors.affiliation: Department of Biomedical Engineering, University of California-Irvine, Irvine, CA, USA.
authors.forename: James V
authors.initials: JV
authors.lastname: Jester
authors.affiliation: Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA; Department of Ophthalmology and Vision Science, School of Medicine, University of California-Davis, Davis, CA 95616, USA. Electronic address: cjmurphy@ucdavis.edu.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Murphy
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism*; D003886:Descemet Membrane / Q000378:metabolism; D055119:Elastic Modulus; D004728:Endothelium, Corneal / Q000502:physiology*; D019573:Epithelium, Corneal / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D017711:Nonlinear Dynamics; D011817:Rabbits
chemical_list: D003094:Collagen
keywords: AFM; Cornea; Elastic modulus; Nonlinear optical high-resolution macroscopy; Rabbit